Lateral pin retention system and method

ABSTRACT

A pin joint includes a pin having a longitudinal axis. A bushing for use with a lateral pin retention system may be positioned around the pin. The bushing includes an arc groove disposed radially about an outer surface of the bushing. A retaining plug for use with the lateral pin retention system includes an engagement head shaped to engage the arc groove and may be attachable to a linkage of a machine.

CROSS-REFERENCED TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No.61/152,842 filed Feb. 16, 2010, which disclosure is incorporated herein.

TECHNICAL FIELD

This invention relates generally to pin joint assemblies and moreparticularly, to a lateral pin retention system.

BACKGROUND

Pin joints are used in a number of applications to rotatably connect twoportions of a machine together, for example, pin joints may be used torotatably connect each structure of a linkage. For example in U.S. Pat.No. 7,309,186, a pin joint may include a bushing, sleeve bearings,inserts, collars, seals and other components disposed about a centralpin. The pin joint is then retained in position by retainers disposed onone or more ends of the pin joint. However, during use, the componentsof the pin assembly may shift out of alignment, which may acceleratewear and failure of the pin joint. For example, the bushing may receivea side load causing the bushing to be biased against a first seal andaway from the second seal. This biasing of the bushing over time maycause the seal to prematurely fail and leak lubricant from the pinjoint, thus leading to premature failure of the pin joint

SUMMARY OF THE INVENTION

In one aspect, a pin joint comprises a pin having a longitudinal axis. Abushing for use with a lateral pin retention system may be positionedaround the pin. The bushing includes an arc groove disposed radiallyabout an outer surface of the bushing.

In another aspect, a retaining plug for use with the lateral pinretention system includes an engagement head shaped to engage the arcgroove.

In yet another aspect, a cap assembly of the retaining plug isconfigured to attach to a linkage of a machine.

In an aspect of the method for maintaining a position of a bushing on apin in a pin joint, the method includes positioning a bushing around thepin. The bushing includes an arc groove disposed radially about an outersurface of the bushing. The method further includes positioning anengagement head of a retaining plug in the arc groove.

In a further aspect of the method, the method includes attaching a capassembly of the retaining plug to a linkage of a machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a machine featuring a linkage incorporating pinjoints.

FIG. 2 is a cross section taken along line 2-2 of FIG. 1 illustrates oneof the pin joints of FIG. 1.

FIG. 3 is a perspective view of a cut away of the linkage of FIG. 1showing the lateral pin retention system in engagement with the bushingof the pin joint.

FIG. 4 is a perspective view of a cut away of the linkage of FIG. 1showing the lateral pin retention system in engagement with the bushingof the pin joint.

FIG. 5 is a side elevation view illustrating the engagement head inisolation.

FIG. 6 is a cross section taken along line 6-6 of FIG. 5 and furtherillustrates engagement head.

DETAILED DESCRIPTION

Referring to FIG. 1, an elevated side view illustrates a machine 10. Themachine 10 may be a wheel loader, back hoe loader, or any other machineincluding a linkage, such as excavators and the like that may utilizethe components described herein. As shown, machine 10 may have astructural frame 12 with a front portion 14 and a rear portion 16. Aplurality of ground supporting members 20, such as tires, wheels, ortracks, are connected to the front portion 14, one of which is shown,and the rear portion 16 of the structural frame 12 through axles, driveshafts or other means (not shown).

An articulated joint 34 pivotally connects the front portion 14 to therear portion 16 by way of a pair of pin joints 38. A linkage 44 ispivotally connected to the front portion 14 of the frame 12 by a pinjoint 45, with a lift cylinder 43 pivotally connected between the frontportion 14 of the frame 12 and the linkage 44. A tilt cylinder 46 isconnected between the front portion 14 and a tilt assembly 48 of thelinkage 44. The linkage 44, the lift cylinder 43, and the tilt cylinder46 may be connected by pin joints and provide the means to raise, lowerand orient an implement 50, such as a bucket, forks, and otherimplements known in the art.

Referring to FIG. 2, a cross section taken along line 2-2 of FIG. 1 thatillustrates the pin joint 45 which may be representative of all of thepin joints in the linkage 44. As shown, the pin joint 45 includes a pin100 and a bushing 102 rotatably positioned on the pin 100. The pin 100and bushing 102 are disposed about a longitudinal axis 104. The bushing102 includes an arc groove 106 that is radially disposed relative to thelongitudinal axis 104 on an outer surface 108 of the bushing 102.

The pin joint 45 may optionally include one or more sleeve bearings 110,inserts (not shown), collars 112, thrust rings 114, and seals 116. Thecollars 112 may be attached to the pin 100 so that during operation ofthe pin joint 45, the bushing 102 rotates relative to the collars 112and the pin 100. The thrust rings 114 may be used to better distributeaxial or side loads applied to the pin joint 45.

The seals 116 may be disposed between the components surrounding the pinto retain a lubricant in the pin joint 45. The seals 116 may be anysuitable type of seal such as a metal-to-metal face seals or can seals.

The pin joint 45 may be retained in the linkage 44 by one or moreretainers 120 disposed on one or more ends 122 of the pin joint 45. Theone or more retainers 120 may be any suitable retention system known inthe art such as the illustrated bolted faceplate.

As shown, the pin joint 45 further includes a lateral pin retentionsystem 130. The lateral pin retention system 130 includes a retainingplug 132 shaped to engage the arc groove 106 in the outer surface 108 ofthe bushing 102. During articulation of the linkage 44, the retainingplug 132 moves about the arc groove 106 providing continuous engagementbetween the retaining plug 132 and the bushing 102, thus providingpositive retention and positioning of the bushing 102 relative to thepin 100.

When installed on a machine 10, the retaining plug 132 is disposedwithin a hole 140 in the linkage 44 coupling so that the retaining plug132 may be held against the bushing 102 and in the arc groove 106. Morespecifically, retaining plug 132 may include an engagement head 150, abiasing member 152, and a cap assembly 154. Further, a fastener (notshown) may be used to attach the engagement head 150, a biasing member152, and a cap assembly 154 together as a single assembly.Alternatively, the retaining plug 132 may be a solid unitary structure.

The engagement head 150 is shaped to ride within and engage the arcgroove 106 to maintain the spacing between the bushing 102 and the othercomponents of the pin joint 45. The biasing member 152 may be a springor resilient material or washer to help maintain the retaining plug inthe arc groove 106. The cap assembly 154 may be threaded for threadedattachment to the hole 140 and maintains the engagement head 150 and thebiasing member 152 in position in the hole 140. Alternatively, the capassembly 154 may be bolted to the linkage 44 as shown in FIG. 3.

Still in reference to FIG. 2, a lubricant refill plug 160 may optionallybe disposed within the arc groove 106. The lubricant refill plug 160permits lubricant to be refilled within the pin joint 45 throughtemporary removal of the retaining plug 132 when the lubricant refillplug 160 is aligned with the hole 140. The lubricant refill plug 160 maybe a zerc or removable fastener such as a screw, plug, cork, or anyother sealing means known in the art.

Referring to FIG. 4, a perspective view of a cut away of the linkage ofFIG. 1 showing the lateral pin retention system 130 in engagement withthe bushing 102 of the pin joint 45. As shown, the arc groove 106extends radially over the outer surface 108 of the bushing 102 andpermits the linkage 44 to rotate relative to the bushing 102 while thelateral pin retention system 130 prevents lateral movement of thebushing relative to the linkage 44.

Referring to FIG. 5, a side elevation view illustrates the engagementhead 150 in isolation. The engagement head 150 may include a concave end170 having a radius 172 similar to a radius of a bottom surface of thearc groove 106 to maximize engagement with the arc groove.

Referring to FIG. 6, a cross section taken along line 6-6 of FIG. 5further illustrates engagement head 150. As shown, the engagement head150 may include a vertical axis 173 and side engagement surfaces 174disposed at an angle 176 to the horizontal which is perpendicular to thevertical axis 173. Angle 176 facilitates maximum engagement between theside engagement surfaces 174 and the side surfaces of the arc groove106. In some configurations, the angle 176 may range between aboutninety-two and one hundred thirty-five degrees from horizontal. In otherconfigurations, the angle 176 may range between ninety-five and onehundred degrees from horizontal.

As shown in FIGS. 5 and 6, the engagement head 150 has a substantiallycylindrical profile 178 into which the side engagement surfaces 174 areformed.

INDUSTRIAL APPLICABILITY

In general, it is believed that the features of the lateral pinretention system disclosed herein provides improved position maintenanceof a bushing of a pin joint while meeting the small packaging, weightand size requirements for modern linkages. When installed on a machine,the arc groove of the bushing and the retaining plug cooperate tomaintain the position of the bushing on the pin. In other words, thissystem may be used to properly position the pin assembly within thejoint during manufacture, repair, or replacement and provides positivepin retention during operation of the joint. In addition, for retrofitapplications, an existing grease hole may be altered to accept theretaining plug and the existing pin joint replaced by a pin joint thatincludes an arc groove.

1. A pin joint comprising: a pin having a longitudinal axis; a bushingdefining a through-hole extending along the longitudinal axis, the pinextending through the through-hole and being rotatably positionedtherewith, the bushing including an arc groove disposed radially aboutan outer surface of the bushing; and a retaining plug configured to bedisposed in a linkage rotatably positioned around the bushing andincluding an engagement head engaging the arc groove to prevent lateralmovement of the bushing relative to the pin when the engagement headengages the arc groove, wherein the retaining plug further includes abiasing member and a cap assembly, wherein the biasing member isconfigured to bias the engagement head away from the cap assemblytowards the arc groove.
 2. The pin joint of claim 1, wherein theengagement head includes a concave end having a radius about equal tothe radius of a bottom surface of the arc groove.
 3. The pin joint ofclaim 2, wherein the engagement head further includes side engagementsurfaces disposed at an angle ranging between about ninety-two and onehundred thirty-five degrees from a horizontal axis that is perpendicularto a vertical axis of the retention plug.
 4. The pin joint of claim 2,wherein the engagement head further includes side engagement surfacesdisposed at an angle ranging between about ninety-five and one hundreddegrees from a horizontal axis that is perpendicular to a vertical axisof the retention plug.
 5. The pin joint of claim 1, further comprising:a first collar disposed on a first side of the bushing, the first collardisposed on the pin; a second collar disposed on a second side of thebushing, the second collar disposed on the pin; a first seal disposed onthe pin and between the first collar and the bushing; and a second sealdisposed on the pin and between the second collar and the bushing;wherein the retaining plug maintains a position of the bushing betweenthe first and second collars.
 6. The pin joint of claim 1, wherein aportion of the engagement head that contacts the arc groove has a shapecorresponding to a shape of the arc groove.
 7. A pin joint systemcomprising: a pin having a longitudinal axis; a bushing defining athrough-hole extending along the longitudinal axis, the pin extendingthrough the through-hole and being rotatably positioned therewith, thebushing including a groove disposed radially about an outer surface ofthe bushing; a linkage rotatably positioned around the bushing; aretaining plug including a first portion fixed to the linkage and asecond portion engaging the groove to prevent lateral movement of thebushing relative to the linkage when the linkage rotates relative to thebushing, wherein the retaining plug further includes a biasing memberconfigured to bias the second portion away from the first portion towardthe groove.
 8. The system of claim 7, wherein the linkage includes ahole for receiving the retaining plug.
 9. The system of claim 8, whereinthe first portion of the retaining plug includes a cap assembly attachedto the hole, and the second portion of the retaining plug includes anengagement head for engaging the groove.
 10. The system of claim 7,wherein the second portion is movable relative to the first portion toengage the groove.
 11. The system of claim 7, wherein the second portionincludes a concave end having a radius about equal to the radius of abottom surface of the groove.
 12. The system of claim 7, wherein thesecond portion is shaped to ride within and engage the groove.
 13. Thesystem of claim 7, further comprising a lubricant refill plug disposedwithin the groove.
 14. The system of 7, further comprising: a firstcollar disposed on the pin and on a first side of the bushing; a secondcollar disposed on the pin and on a second side of the bushing oppositethe first side; a first seal disposed on the pin and between the firstcollar and the bushing; and a second seal disposed on the pin andbetween the second collar and the bushing.
 15. A pin joint comprising: apin having a longitudinal axis; a bushing defining a through-holeextending along the longitudinal axis, the pin extending through thethrough-hole and being rotatably positioned therewith, the bushingincluding a groove disposed radially about an outer surface of thebushing, the groove defining two side surfaces generally facing oneanother and a bottom surface; a retaining plug configured to be disposedin a linkage rotatably positioned around the bushing and including anengagement head engaging the groove, wherein the engagement headincludes: two side engagement surfaces engaging respective two sidesurfaces of the groove when viewed in a plane parallel to thelongitudinal axis, and a concave end engaging the bottom surface of thegroove, the concave end having a curvature radius equal to the radius ofthe bottom surface when measured with respect to the longitudinal axis.16. The pin joint of claim 15, further comprising a linkage rotatablypositioned around the bushing, the linkage including a hole forreceiving the retaining plug.
 17. The pin joint of claim 16, wherein theretaining plug includes a cap assembly attached to the hole and theengagement head engaging the groove.
 18. The pin joint of claim 17,wherein the engagement head is movable relative to the cap assembly.